Air brake



April 20, 1.937. g. A. CAMPBELL 2,077,515

AIR BRAKE Filed Nov. 25, 1934 5? 2 55 y as I Ema/.8

IL I 46z Jnventor (Ittomegs Patented Apr. 20, 1937 UNITED STATES AIRBRAKE Charles A. Campbell, Watertown, N. Y., assignor to The New YorkAir Brake Company, a corporation of New Jersey Application November 23,1934, Serial No. 754,489

10 Claims.

This invention relates to air brake systems and particularly toautomatic means for draining Water from the main reservoir.

The accumulation of water which condenses from the compressed air in themain reservoir, is a Well known source of operating difficulties.Heretofore various means for periodically draining off this water havebeen proposed, but none known to me has proved successful underpractical operating conditions. Some of the prior art devices wereintended to operate periodically in response to application or releaseof the brakes.

The present invention falls in this general class but involves novelfeatures which enable it to meet the practical requirements 'of service.

The device includes a venting drain valve and a timed actuating means,which when put into action, preferably by the development of brakecylinder pressure, opens the vent valve, holds it open for a definitetime interval and then closes it. This time interval is so chosen withreference to the capacity of the vent, and the probable maximumaccumulation of water between venting actuations, that when the valveopens it will stay open at least long enough for the maximumaccumulation of water to be swept through and clear of the valve. Inpractice the valve can be designed to operate in this waywith an openperiod of about second.

The valve is mounted above the reservoir, or at any rate above thehighest water level contemplated, and its water intake connection ispreferably in the form of a dip pipe leading to a sump formed in thelowest portion of the reservoir.

Consequently water is not retained in the valve between actuationsthereof, but at each actuation the valve is swept clear of water andremains free of water until it again functions.

Because of the features above enumerated the tendency of the valve tofreeze up in cold weather is minimized or completely eliminated. Inprior art devices the water accumulated in or near the valve andfreezing up was a common cause of failure in Winter.

Another feature conducive to certain and precise operation is the use offlexible diaphragms in lieu of pistons, Their free movement offerscertainty of operation, and their small displacement permits precisetiming with a timing chamher of minimum volume, a feature of momentWhere actuations are frequent and the timing air cannot be otherwiseusefully applied.

Another feature of the invention is the use with the automatic valve ofa second manually operable valve whose mount sorvesas a sumpfrom whichthe dip pipe of the automatic valve leads.

Other novel and useful features will be recognized from a considerationof the description of a preferred embodiment illustrated in theaccompanying drawing. 5

In the drawing,

Fig. 1 is a vertical axial section through the automatic drain valve.

Fig. 2 is an elevation, partially broken away, showing two mainreservoirs connected in tandem l0 and automatic drain valves, oneconnected with each reservoir, and both arranged to be put into actionby pressure developed in the brake cylinders.

Referring to Fig. 2, the main reservoir volume 15 is made up of twodrums 4 and 5, connected'at 6 and supplied with compressed air throughpipe 1 which leads from the discharge of the usual compressor (notshown). The brake system is fed with compressed air by an engineersbrake 20 valve of any suitable form (not shown) such brake valve beingconnected to pipe 8.

The operation of the brake valve admits and exhausts air to and frombrake cylinders 9, either directly or through automatic valves (notshown), 25 depending on the type of brake system used. The type ofsystem is immaterial. Pipe II is connected with the cylinders 9 andhence is subject to whatever pressure exists from time to time in thecylinders. 30

Screwed into an aperture at the lowest point in each drum is a fittingl2 which forms a small sump I 3, and attached to the lower side of thefitting is a manually operable drain cock l4. Opening of the cock willdrain the sump and con- 35 sequently the corresponding drum. This isuseful on dead equipment or in case of derangement of the automaticvalve.

Diametrically opposite each fitting l2 and hence at the top of thecorresponding drum a 0 bushing I5 is screwed into an aperture in thedrum and carries a dip pipe l6 whose open lower end is in sump I3.Screwed into each bushing I5 is a corresponding 90 pipe bend I! whichleads to a corresponding drain valve. 45

As the two drain valves are functionally and mechanically identical, adescription of one will suffice, and such description will now be givenwith reference to Fig. 1.

The housing of the main valve comprises four 0 components, a main body2!, a rear cap 22, a front cap 23 and a combined diaphragm seat andbaffle 24 mounted within the front cap.

In the main body 2| is an annular timing chamber 25 separated by anannular wall 26 and dished 55 head 21 from a combined valve chamber anddiaphragm chamber 28. At the rear end of chamber 28 is a port surroundedby the annular bead or valve seat 29. A passage 3| leads from cham- 5ber 25 to the port through said seat.

In the rear end of body 2| is a recess or cavity 32 having a marginalseat for the periphery of a combined gasket and flexible diaphragm 33,of rubber-like or other suitable material. The periphery of member 33 isclamped against the seat by the rear cap 22 which is bolted in place asshown and encloses a chamber 34 on the outer side of the diaphragm.

Chamber 34 is connected by passage 35 with pipe 36, which is screwedinto the tapped open.- ing 31. A gasket 38 prevents leakage from passage35. Thus diaphragm 33 is forced inward (to the right, in the drawing)when pressure builds up in the brake cylinders.

In chamber 32, and in thrust relation with the inner face ofdiaphragm33, is a disk 39 mounted onthe. end ofv atubular member 4!.Member 4| slides axially'and fits closely in a guideway formed in body2| and. leading through passage 3| and seat 29. The inner end of tubularmember 4| is tapered as shown and adjacent disk 39 there are; throughports 42, four being indicated.

The disk 39 carries an annular: gasket 43 which attheinner limit of:motion of diaphragm 33 and disk 38 seals on a seat 44 formed in body 2|.A

choke 45is. mounted in the bore of tubular member 4| and limits the fiowtherethrough. The chamber: 32 is vented to atmosphere at 46.

The front cap 23 has at its front center a tapped connection 41 for'pipeThere is also a tapped. bottom. connection 48 for a drain pipe 49',which may lead; to any'suitable point of discharge. Both connections 41and 48 communicate with a chamber 5| and the first-named is surroundedby a valve seat bead. 52. There is also a tapped connection 53: whichleads to chamber 54 between a pair of differential diaphragms about tobe described. A pipe 55 conducts main reservoir air from. pipe 8through. filter 56 to chamber 54, so that this chamber is always.subject to main. reservoir pressure.

The diaphragms just. mentioned are. a large diaphragm 51 and a smalldiaphragm 58, each.

of which. isof rubber-like or other suitable material, and each of whichis clamped at its periphery and there functions as a gasket. The.smaller diaphragm is clamped by spacer 24 against a seat in cap: 23, andthe larger is clamped between the spacer 24 and cap 23, on the one:hand, and. body 2| on the other. The spacer 24 has' a port: 59 ofmoderate capacity and serves as. a. baflie between connection 53 and thecenter portion of chamber A flanged spacer 6| connects thecenters ofthe60 diaphragms 51 and 58'and has bosses which extend through holes at thecenters of the. diaphragms. A disk 62 andv nut 63? are used to en:- surea sealed connection to diaphragm 51. A port 64 of limited fiow capacityleads through 65 spacer 6| and oifers a moderately restrictedconnection' between chambersv 54 and 28..

Similarly a sealed connection with. diaphragm 58 is. secured by the useof valve disk 65 and screw 66. Disk 55 has an annular recessin which isfixed a gasket 61 which normally seals against seat 52.

Guided in chamber 28 and normally engaging seat 29 is a valve 68 hereshown as composed of rubber-like material. It' is stiffened by a metaldisk 69 having a serrated periphery which serves to center the valve inchamber 28. A coil compression spring H is interposed between the valve38 and the nut 63 on the spacer 6|.

Operation Under normal running conditions with brakes released, chambers54 and 28 are at main reservoir pressure, with valve 68 closed againstseat 29. Hence pressures on the opposite faces of diaphragm 51 are equaland main reservoir pressure acting on diaphragm 58 holds valve gasket 61against seat 52. It will be observed that the area within seat 52 issmaller than the effective area of diaphragm 58.

At this time brakes are released so chamber 34 is at atmosphericpressure. Tubular member 4| is retracted, allowing valve 68 to seat andventing chamber. 25. to atmosphere via passage 3|, choke 45, ports. 42,chamber 32 and passage 46.

When a brake application is made diaphragm 33v will be forced inward.Member 4| first seals on valve; 68 and then unseats the valve. Thissubstantially closes the vent from. chamber 25, but gasket 43 produces acomplete seal when it engages seat 44. The effect is to connect chambers25 and 28 through alarge port, putting diaphragm 51 out of balance andcausing valve 65 to open. Flow at oncestarts from chamber 54 throughport 64 to chambers 28 and 25, which are connected as described. Whenequalization is approached valve 65 will again close.

The parts are so proportioned that the duration. of the open condition.of valve 65 will ensure the discharge of all water likely to be present,so that sump |3,.pipes I6 and I5, and chamber 5| are swept clear. A.period of about /2 second is preferred in practice, but this may bemodified to suit particular cases. Timing can be changed by changing,for example, the capacity of port 64 or the volume of chamber 25.

When the brakes are released the retreat of diaphragm 33 and member 4|allows valve 68 to close and then vents chamber 25, conditioning thedevice for. another operative cycle. It should be noted that choke 45delays the venting of chamber" 25, so that a quickly repeated brakeapplication will not open the drain valve or will open it for: a shorterperiod. While the various details are all considered useful, they aresubject to modification, and some may in certain cases i be omitted. Thespecific embodiment described is intended to be illustrative and notlimiting.

For example, the development and subsequent release of pressure inchamber 34 will cause the valve to perform its operative cycle. Thisshould occur periodically and connection with a brake cylinder orcylinders is a familiar expedient and one already proposed in this art.It is recognized, however, that chamber 34 might be connected to anyspace in which a suitable operating pressure is temporarily developedfrom time to time. The size of diaphragm 33 may, if necessary, bemodified according to the pressure so available.

What is claimed is,--

1. The combination of a brake system includ ing a reservoir; a normallyclosed drain valve for discharging liquid from said reservoir; apressure motor arranged to be actuated by pressure fluid deriveddirectly from said reservoir, connected to actuate said valve andarranged when put into action to perform a timed cycle in which it openssaid valve for a definite period, then closes the same and ceases toact; and valve means distinct from said brake system but responsive topressure variations in a portion of said brake system other than saidreservoir for putting said motor means into action.

2. The combination of. a brake system including a reservoir; a normallyclosed drain valve for discharging liquid from said reservoir; apressure motor arranged to be actuated by pressure fluid deriveddirectly from said reservoir, connected to actuate said valve andarranged when put into action to perform a timed cycle in which it openssaid valve for a definite period, then closes the same and ceases toact; valve means distinct from said brake system but responsive topressure variations in a portion of said brake system other than saidreservoir for putting said motor means into action; and means associatedwith said motor means and serving to prevent the same from being putinto action for a definite period following the performance of anoperative cycle.

3. The combination of a drain valve; means urging said valve closed;motor means connected to actuate said valve and comprising a pair ofWorking spaces separated by a movable abutment, there being a restrictedpressure equalizing connection between said spaces; means for supplyingpressure fluid to one working space and thence through said equalizingconnection to the other working space; a timing chamber; valve meansserving to connect said timing chamber selectively to exhaust and tosaid other Working space; and means for shifting the last-named valvemeans.

4. The combination of a drain valve; means urging said valve closed;motor means connected to actuate said valve and comprising a pair ofworking spaces separated by a movable abutment, there being a restrictedpressure equalizing connection between said spaces; means for supplyingpressure fluid to one working space and thence through said equalizingconnection to the other working space; a timing chamber; valve meansserving to connect said timing chamber selectively to exhaust and tosaid other working space; means for shifting the last-named valve means;and means for delaying the exhaust of pressure fluid from said timingchamber.

5. The combination of a brake system including a reservoir; a drainvalve arranged to discharge liquid from said reservoir; means urgingsaid valve closed; motor means comprising a pair of working spaces and amovable abutment interposed between said spaces, there being arestricted pressure equalizing connection between said spaces; anoperative connection between said abutment and valve; means forsupplying pressure fluid to one of said working spaces and thencethrough said equalizing connection to the other of said working spaces;a timing chamber; valve means serving to connect said timing chamberselectively to exhaust and to said second working space; and motor meansresponsive to pressure in a portion of the braking system for shiftingthe last-named valve means.

6. The combination of a drain valve; motor means comprising a pair ofworking spaces and a movable abutment subject to the opposing pressuresin said spaces, there being a restricted pressure equalizing connectionbetween said spaces; an operative connection between said abutment andvalve; means for supplying pressure fluid to one working space andthence through said equalizing connection to the other working space,

means comprising a movable abutment subject to pressure in thefirst-named working space and connected to urge said valve in a closingdirection; a timing chamber; valve means serving to connect said timingchamber selectively to exhaust and to said second working space; andmeans for shifting the last-named valve means.

7. The combination of a drain valve; motor means comprising a pair ofworking spaces and a movable abutment subject to the opposing pressuresin said spaces, there being a restricted pressure equalizing connectionbetween said spaces; an operative connection between said abutment andvalve; means for supplying pressure fluid to one working space andthence through said equalizing connection to the other working space;means comprising a movable abutment subject to pressure in thefirst-named working space and connected to urge said valve in a closingdirection; a timing chamber; valve means serving to connect said timingchamber selectively to exhaust and to said second working space; meansfor shifting the last-named valve means; and means for delaying theexhaust of pressure fluid from said timing chamber.

8. The combination or a drain valve; means urging said valve closed;motor means connected to actuate said valve and comprising a pair ofworking spaces separated by a movable abutment, there being a restrictedpressure equalizing connection between said spaces; means for supplyingpressure fluid to one working space and thence through said equalizingconnection to the other working space; a timing chamber; a normallyclosed poppet valve controlling the communication between said timingchamber and said other working space; a shiitable member having adischarge port through which said timing chamber is normally vented; andmeans for shifting the last-named member into sealing engagement withsaid poppet valve to close said discharge port and then unseat saidpoppet valve.

9. The combination of a drain valve; means urging said valve closed;motor means connected to actuate said valve and comprising a pair ofworking spaces separated by a movable abutment, there being a restrictedpressure equalizing connection between said spaces; means for supplyingfluid to one working space and thence through said equalizing connectionto the other working space; a timing chamber; a normally closed poppetvalve controlling the communication between said timing chamber and saidother working space; a shiftable member having a discharge port throughwhich said timing chamber is normally vented; and fluid pressureoperated means for shifting the last-named member into sealingengagement with said poppet valve to close said discharge port and thenunseat said poppet valve.

10. The combination with a receiver having a liquid-collecting sump, ofa drain valve connected with said sump and located wholly above theliquid level therein; motor means capable of being put into action toopen said valve and then after a definite time interval, sufficient toensure discharge of substantially all liquid from the sump, to closesaid valve; and means rendered effective by the performance of one suchcycle to preclude its recurrence for a definite time interval.

CHARLES A. CAMPBELL.

